Wireless telephony has grown at an exponential rate over the past several years. As more people use wireless telephones, service providers must add additional equipment in order to keep up with the demand for service. Thus, there are several manufacturers selling such mobile telephony equipment, wherein some equipment provides features and services not available on other systems. This sometimes becomes a problem when a wireless unit moves out of the coverage area of its home office and "roams".
Currently, there are standards for systems communications when a wireless unit is roaming. When a call is made to a wireless telephone, the incoming call is directed to the home switching office ("home system"), or MTSO. The home system performs a lookup on the wireless unit's directory number and determines that the wireless unit is not in the coverage area. The home system then determines the last location of the wireless unit and sends a message to that MTSO to determine if the wireless unit is still there. If it is, then the serving system sets up a trunk between the home and serving systems.
Conversely, when a wireless unit attempts to place a phone call with a foreign wireless system, it "registers", wherein its identification is stored in a specific location in memory in the MTSO. The serving system then sends out a query to locate the home system of this wireless unit. The home system sends some records of the wireless unit to the serving system. A call can then completed through the facilities of the serving system.
In the above two scenarios, the serving system is the controlling system for the roaming wireless unit. The serving system may not necessarily have the same facilities, functions and services that the home system has. For example, some systems provide the service of voice dialing with subscriber-specific voice dialing lists. Such lists are very memory-intensive, and are, thus, not transmitted from a home system to a serving system, because such transmission would take a lot of time and a lot of resources, and the serving system may not be able to support this feature in the first place. Therefore, the wireless unit loses features when it roams.
Furthermore, certain personal communication services (PCS) provide "dial tone" interface to the PCS system. In dial tone PCs, a path to the switch is set up whenever the wireless unit performs the equivalent of an "offhook". The MTSO then sends a dial tone to the wireless unit and the wireless unit sends digits which are then translated into dual tone multifrequency (DTMF) signaling, and the call is processed as if it were a line origination. However, due to the limited deployment of such PCS systems, it is not currently possible for a PCS wireless unit to roam.
Therefore, a problem in the art is that there is no system for providing a wireless unit with all of the features and services of its home system which is served by a foreign system.